Lamp stem head



Nov. 13,1962 s. E. SWASEY ETAL 3,063,130

LAMP STEM HEAD Filed Nov. 9, 1959 INVENTORS SAMUEL E. SWASEY JOHN W. WALLACE ERNEST F. STACEY BY w.

ATTO NEY United States Patent Otlice Patented Nov. 13., 1962 aware Filed Nov. 9, 1959, Ser. No. 851,916 Claims. (Ci. 29-25.ll9)

This invention relates to the manufacture of electric lamps and more particularly to apparatus for fabricating stems in the lamp manufacturing operations.

in the manufacture of many types of incandescent lamps, such as those normally used for domestic lighting purposes for example, the lamp filament is usually connected, electrically and mechanically, to the inner ends of a pair of lead-in wires which are supported by and extend through the press portion of a glass stem, the flare of which is sealed to the open end of the lamp envelope to provide a closed container. In this type of construction, accurate orientation of the lamp filament within the lamp envelope presents no great problem because the inner ends of the lead-in wires on which the filament is mounted are not apt to be accidentally displaced from their desired locus during subsequent lamp manufacturing operations. On the other hand, in the manufacture of miniature incandescent lamps, such as telephone switchboard lamps for example, the lamps are so small that very serious practical manufacturing difficulties have made it impractical to utilize the stem type of construction with automatic lamp manufacturing equipment. One of these difficulties is the establishment and maintenance of accurate orientation of the several work-supporting members and the accurate positioning of the work therein.

In the manufacture of a stem type of lamp mount, a glass flare, a pair of lead-in wires and an exhaust tube are usually assembled sequentially in a certain spaced relationship with respect to one another, the throat of the flare is heated to a plastic state and then engaged by a pair of dies to form a stem press, and air under pressure is introduced into the exhaust tube to blow out a port in the stem press. The manufacture of this stem type of lamp mount is usually eifected on automatic equipment, such as the apparatus shown and described in US. Patent 2,637,144 for example. In conventional automatic stem manufacturing equipment, a plurality of heads for supporting the flares and the exhaust tubes are mounted on one conveyor and a plurality of heads for supporting the lead-in wires are mounted on another conveyor, the former conveyor being above and in register with the latter conveyor and the heads on the former conveyor being above and in register with the heads on the latter conveyon- These conveyors advance in synchronism to move the aligned heads thereon to a pinrality of work stations to effectuate fabrication of the stem.

It will be appreciated, particularly by those skilled in the art, that not only must the cooperating pairs of heads on the two conveyors be kept in accurate alignment but the several work-supporting or work-gripping devices thereon must also be maintained in pre-determined positions both with respect to the structures to which they are attached and particularly with respect to one another. It will also be appreciated particularly by those skilled in the art, that the maintenance of these close tolerances'become increasingly critical as the size of the stern being manufactured gets smaller. The smaller the inside diameter of the throat of the flare get-s, the more ditficult it becomes to position and maintain in position the lead-in wires and the exhaust tube which are to be assembled with the flare into a unitary structure. Thus it has been the practice, in the manufacture of many miniature incandescent lamp types to utiliZe some other type of mount structure instead of the stern type, such as a bead mount for example. The bead mount and other types of alternative structures do, however, have their disadvantages, the major one being inability to exercise accurate control over the positioning of the filament in the lamp envelope. This is particularly unfortunate since, in many cases, accurate positioning of the lamp filament in the lamp envelope is more critical in the smaller lamps than it is in the larger ones.

In view of the foregoing, an object of this invention is to provide a new head construction for automatic stem making machines.

Another object is to provide a new stem machine head which may be utilized to make stem type lamp mounts substantially smaller than have been possible heretofore.

These and other objects, advantages and features are attained, in accordance'with the principles of this invention by providing a unitary stem machine head, i.e., a single head, on which all of the work-supporting or work-gripping devices are mounted, on a single conveyor. This makes possible the establishment and maintenance of the several Work holders thereon in precise pro-determined locations, particularly with respect to one another, within very closely held tolerances. This makes the second conveyor unnecessary and thus eliminates the untolerable variables, such as slight misalignment of the cooperating pairs of heads on the two conveyors for example.

In the specific embodiment of the invention illustrated in the accompanying drawing,

FIGURE 1 is a side elevational view of a stem machine head embodying the invention.

FIGURE 2 is an exploded view of the stem machine head of FIGURE 1.

FIGURE 3 is a plan view of the head of FIGURE 1 on an enlarged scale.

FIGURE 4 is a side elevational view of the head of FIGURE 1 on an enlarged scale, the side shown in FIG- URE 4 being the side opposite the one shown in FIG- URE 1.

Referring now to the drawings, particularly FIGURES 1 and 2 thereof, the base member of the stem machine head illustrated therein is a stern head body 12, on which the several work-supporting devices and their associated parts are mounted, the body 12, in turn, being attached by bolt 9 to a mounting link 11 of the stem machine conveyor. A flare holder 14 is provided with a seat 16 (FIG. 2) on which a glass flare may be positioned. The flare holder 14. is provided with an elongated slot 18 through which it may be adjustably mounted on body 12 by screw 20 (FIG. 1). One end of a flare jaw 22 is in register with seat 16 of the flare holder 14 and serves to retain a flare in the seat 16. The other end of the flare jaw 22 is pinned to one end of a flare jaw rod 24. The flare jaw rod 24 extends through and is reciprocable within body 12, the other end thereof being provided with a spring 26 which is contained between spring collar 23 pinned to rod 24. and spring sleeve 30 which is freely movable on rod 24. A spring bracket 32, attached at one end thereof to the top of body 12, is provided with an aperture at the other end thereof, through which flare jaw rod 24 extends. Thus the bracket 32 defines a stop for the upward travel of the floating sleeve 30 and the spring 26.

An exhaust tube is supported and gripped intermediate its ends by a pair of jaws 34 and 36. law 34 is fixedly mounted on an outer face of flare holder 14 which, as

' 3 noted above, is attached to body 12. As may be noted in FIGURE 2, the jaw 34 is provided with an elongated mounting slot 38 through which mounting position adustments may be made to acomrnodate exhaust tubes of different diameters. Jaw 36 is provided with a central aperture 37 (FIG. 2) through which pivot post 4 freely extends. The pivot post 40 extends thorugh the body 12 and is retained therein by collar 42 (FIG. 4). The jaw 36 is retained in position on the post 40 which extends therethrough by a pair of collars 44 (FIGS. 2 and 4). The jaw 36 is urged to a normally closed position with respect to jaw 34 by a spring 46, one end of which is attached thereto, the other end of the spring being attached to pin 43 mounted on body 12.

The wire block assembly used to help position the leadin wires at the time of feeding thereof to the stem head as Well as to protect them from the heat developed during stem fabrication is, in the specific embodiment of the in- Vention disclosed in the accompanying drawings, specifically designed for use with the lead-in feeding method taught in US. Patent 2,762,110 issued to L. J. Ward on September 11, 1956 and utilizing apparatus of the type disclosed in the co-pending application of Swasey et al., Ser. No. 757,993, filed August 29, 1958, entitled Lead- Wire Feeding Apparatus."

In accordance with that method a length of wire slightly longer than the length of two lead-in Wires is bent at its longitudinal center and pushed dOWn through the throat of the flare so that it assumes a hairpin-like configuration with the bight thereof lying within the wire block assembly.

The wire block assembly comprises a stationary block 52 attached to body 12 at 53 (FIG. 2) and a movable block 54 pinned to the lower end of pivot post 43' at 55 :(FIG. 4). A lead-in wi're stop 56 is attached to the inner face of block 54 by screw 58 (FIGS. 1 and 4). Thus when the hairpin-like wire is fed through the throat of the flare and down into the wire block assembly, it lies within the cut-out 60 in the stationary wire block 52 (FIG. 2) and the bight thereof comes to rest on the stop 56 in the movable wire block 54. When a pair of lead-in wires are fed to the stem head instead of a hairpin-like wire as just described, the wire block assembly would, of course, be modified to accom- 'modate them, such as by providing a pair of suitable pockets therefor for example.

The pivot post 40, to one end of which the movable wire block 54 is attached, is provided at its other end with a pring lever 62 pinned thereto. A pin 64 upstanding on spring lever 62 cooperates with a pin 66 upstanding on the stem machine conveyor mounting link 11 to support a pair of springs 68 which extend therebetween. Since the movable block 54 swings about 180 degrees from its closed position with respect to the stationary block 52 to its fully open position, the relative disposition of the springs 68 is such that the movable block 54 is spring-loaded in both the closed and the open positions.

A detector button 7%, pinned to the top of flare jaw rod 24, provides a means through which the presence or absence of a flare may be detected.

A wire spreader block 72 (FIGS. 1 and 4) is attached to the flare jaw 22 at 23 (FIG. 2). The wire spreader block 72 has grooves therein within which the legs of a substantially U-shaped relatively stifl wire 74 lie, the wire 74 being secured within the block 72 by a clamp 76. The free ends of the legs of the U-shaped wire 74 engage the legs of the hairpin-like lead-in wire and keep them spread apart the desired amount.

A plurality of stem heads of the type shown in the accompanying drawing and described above may be'employed with an automatic lamp stem fabricating apparatus of the type shown in the Gardner et al. Patent 2,637,144 in which the upper conveyor chain only is used, the stem head body 12 of each stern head being attached to the conveyor chain by its mounting link 11. The conveyor chain is driven by suitable means to advance the stem heads mounted thereon to a plurality of stations at which suitable devices are located to effect feeding of the work pieces to their respective work-holding devices thereon. For clarity of illustration, the articles of work, which comprise a flare 1, a length of wire 2 and an exhaust tube 3, have been illustrated in FIGURE 4 only.

In operation, as a stem head moves toward the flare loading station, a stationary bar cam (not shown), lying in the path traversed by the flare jaw rod 24, pushes the rod 2d upwardly, thus raising the flare jaw 22 which is pinned thereto. Thus when the stern head arrives at the flare feeding station the flare jaw 22 is in the open position. At the flare feeding station, a flare l is fed to and positioned on the seat 16 therefor on the flare holder 14. As the stem head moves out of the flare feeding station, the end of the flare jaw rod 24 moves off of the aforesaid stationary bar cam thus permitting the spring 26, which was compressed by the upward travel of rod 24, to drive the rod 24 downwardly and move the flare jaw 22 into gripping engagement with the flare i seated on the flare holder 14.

Since it is neither necessary nor desirable to feed other work pieces to the stem head if for some reason no flare has been fed thereto, means, including detector button 70, are provided for automatically accomplishing this. After the flare jaw 22 has been returned to its closed position with respect to the flare holder 14, and before the stem head reaches the next article-feeding station, the detector button 74} will normally strike and deflect a contact arm (not shown) lying in its path. If this contact is made, it indicates that a flare is being carried by this stem head and subsequent article-feeding devices are permitted to feed to this head. However, if no flare is present, the flare jaw rod 24 will have dropped down further in its return stroke and the detector button 70 will pass beneath rather than strike and deflect the aforesaid contact arm. In the absence of this contact, a suitable relay system connected to the aforesaid contact arm prevents the subsequent feeding of work-pieces to this head.

The next article of work to be fed to the stern head is the length of wire 2 which, a indicated above. is bent into hairpin-like configuration as it is moved through the throat of the flare 1. The wire 2 is advanced by its carrier toward the stem head from the side thereof at a point below the wire spreaders 74 and above the flare 1 (FIG. 4). As the wire 2 is pushed down through the throat or the flare and begins to assume its hairpin-like shape, the lead-in wire spreaders 74 keep the legs of the wire 2 from coming together so closely that subsequently an exhaust tube cannot be fed therebetween. The wire 2 is pushed through the throat of the flare 1 until the legs thereof pass through the cut-out 60 in the stationary wire blocl; 52 and the bight thereof approaches engagement with the stop 56 in the movable wire block 54.

After the stem head leaves the wire-feeding station and before it arrives at the exhaust tube feeding station. a suitable stationary cam (not shown), lying in the path traversed by the pivotally mounted exhaust tube jaw 36. swings the jaw 36 open and maintainsit open until after the exhaust tube 3 has been positioned in the fixed exhaust tube jaw 34 by the exhaust tube transfer means. As soon as the exhaust tube has been so positioned, the jaw 36 rides off of the cam which opened it, thus permitting the spring 46 to drive the jaw 36 to its closed position in gripping engagement with the exhaust tube.

With the several work pieces now held in proper spaced relationship in-the stem head, the conventional stem fabricating operations are performed thereon, such as described in the aforementioned Gardner et a1. Patent 2,637,- 144 for example. One of the features of the stem head of this invention is that after the stem pres has been formed, there is no need to transfer the work to another machine or another conveyor system for the performance of further operations on the work, such as wire shaping, filament mounting, etc. After the stern press has been formed, the article is continued to be held by the exhaust tube jaws 34 and 36, and the flare holder 14 and flare jaw 22. However, to permit further work on the article, a suitable arm (not shown) is advanced into engagement with the movable wire block 54 and pushes it open, causing it to swing about 180 degrees counter-clockwise as viewed in FIGURE 3, thus permitting access to the legs of the wire 2 by suitable tools and working devices. The block 54 is retained in the open position by springs 68.

What we claim is:

1. A head for a lamp stem fabricating machine in which an exhaust tube, at least one lead-in wire and a flare are assembled and fabricated into a unitary structure, a single conveyor mounting said head, said head comprising: a body member; a flare holder mounted on said body member; a pair of jaws for supporting said exhaust tube, mounted on said body member above and in register with said flare holder; and a wire block assembly mounted on said body member beneath and in register with said flare holder, said wire block assembly comprising a stationary wire block and a movable wire block, said movable wire block being pivotally mounted for opening and closing with respect to said stationary wire block, in order to preliminarily position the wire when the movable block is closed and permit working on the lower end of the wire when the movable block is open.

2. A head for a lamp stem fabricating machine in which an exhaust tube, at least one lead-in wire and a flare are assembled and fabricated into a unitary structure, a single conveyor mounting said head, said head comprising: a body member; a flare holder mounted on said body member; a pair of jaws for supporting said exhaust tube, mounted on said body member above and in register with said flare holder; and a wire block assembly mounted on said body member beneath and in register with said flare holder, said wire block assembly comprising a stationary wire block and a movable wire block, said movable wire block being pivotally mounted for opening and closing with respect to said stationary wire block, in order to preliminarily position the wire when the movable block is closed and permit working on the lower end of the wire when the movable block is open, one of said wire blocks having a cut-out formed therein for receiving said lead-in wire and the other of said wire blocks being provided with a stop for said lead-in wire.

3. A head for a lamp stem fabricating machine in which an exhaust tube, at least one lead-in wire and a flare are assembled and fabricated into a unitary structure, a single conveyor mounting said head, said head comprising: a body member; a flare holder mounted on said body member, said flare holder having a seat for said flare; a flare jaw overlying said seat of said flare holder, said flare jaw being reciprocable into and out of engagement with a flare disposed in said seat of said flare holder; a pair of jaws, for supporting said exhaust tube, mounted on said body member above and in register with said flare holder; and a wire 6 block assembly mounted on said body member beneath and in register with said flare holder, said wire block assembly comprising a stationary wire block and a movable Wire block, said movable wire block being pivotally mounted for opening and closing with respect to said stationary wire block, in order to preliminarily position the wire when the movable block is closed and permit working on the lower end of the wire when the movable block is open.

4. A head for a lamp stem fabricating machine in which an exhaust tube, at least one lead-in wire and a flare are assembled and fabricated into a unitary structure, a single conveyor mounting said head, said head comprising: a body member; a flare holder mounted on said body member, said flare holder having a seat for said flare; a flare jaw overlying said seat of said flare holder, said flare jaw being reciprocable into and out of engagement with a flare disposed in said seat of said flare holder; a pair of jaws for supporting said exhaust tube, mounted on said body member above and in register with said flare holder; and a wire block assembly mounted on said body member beneath and in register with said flare holder, said wire block assembly comprising a stationary wire block and a movable wire block, in order to preliminarily position the wire when the movable block is closed and permit working on the lower end of the wire when the movable block is open, said movable wire block being pivotally mounted for opening and closing with respect to said stationary wire block, one of said wire blocks having a cut-out formed therein for receiving said lead-in wire and the other of said wire blocks being provided with a stop for said leadin wire.

5. A head for a lamp stem fabricating machine in which an exhaust tube, a pair of lead-in wires and a flare are assembled and fabricated into a unitary structure; a single conveyor mounting said head, said head comprising: a body member; a flare holder mounted on said body memher; a pair of jaws for supporting said exhaust tube, mounted on said body member above and in register with the flare holder; a wire block assembly comprising a stationary wire block and a pivoted wire block cooperating therewith to position the lower ends of the lead-in wires; and stifr wire legs mounted on said body member above the flare holder, the free ends of the legs engaging the upper ends of the lead-in wires and keeping them spread apart.

References Cited in the file of this patent UNITED STATES PATENTS 1,655,140 Pagan Jan. 3, 1928 1,655,141 Fagan et a1 Jan. 3, 1928 2,535,630 Gartner'et al Dec. 26, 1950 2,637,144 Gardner et al May 5, 1953 2,891,356 Lindsay June 23, 1959 FOREIGN PATENTS 293,313 Great Britain Jan. 17, 1929 

